GROUP II. BRYOPHYTA. 315 



bryonic organ ; but it persists, acting, when sufficiently developed, 

 as the organ of absorption and attachment, throughout the life of 

 the Moss-sporophyte, because the sporophyte, since it does not 

 become free and independent, does not altogether develope beyond 

 the embryonic stage. In most forms the epibasal half of the 

 oospore also gives rise to a longer or shorter stalk, the seta, by the 

 elongation of which the capsule is raised up out of the calyptra. 

 In those Hepaticse which have a seta, its elongation, and the 

 consequent rupture of the calyptra, takes place suddenly when the 

 capsule is already mature and the spores fully developed ; in the 

 Musci its elongation is gradual, whilst the capsule is still rudi- 

 mentary, and the rupture of the calyptra takes place relatively 

 early. In the Hepaticse and some Musci (Sphagnaceae, Phascum, 

 Ephemerum) the whole of the ruptured calyptra remains as a 

 sheath, the vaginula, round the base of the seta : but in the 

 higher Musci (most Bryineae) the calyptra is ruptured trans- 

 versely into an upper and a lower half ; the latter constitutes the 

 vaginula, whereas the former is carried up as a cap on the top of 

 the capsule. In some forms, where the true hypobasal foot is 

 rudimentary (some Jungermanniaceae and Bryinese) and is function- 

 less, the base of the seta becomes dilated to form a false foot 

 (epibasal), which performs the functions of attachment and ab- 

 sorption. 



The body developed from the oospore, which constitutes the 

 asexual generation or sporophyte of the Bryophyta, is termed the 

 sporogonium. With regard to its general morphology it may be 

 considered (except in Ricciese) to present differentiation into root 

 and shoot ; the foot, however rudimentary, developed from the 

 hypobasal half of the oospore, represents the root ; the capsule and 

 the seta (when present), developed from the epibasal half of the 

 oospore, represent the shoot. The shoot is in no case differentiated 

 into stem and leaf. In the Riccieae the products of the hypobasal 

 and epibasal cells are quite similar, so that the whole thalloid 

 sporogonium consists only of a capsule. Hence, whilst it is the 

 rule in the Bryophyta that sporogenous cells are only developed in 

 the shoot-portion of the sporophyte, that is, are derived only from 

 the epibasal cell, in the Ricciese the derivatives of the hypobasal 

 cells are also sporogenous. 



The sporogonium is not an independent sporophyte, but remains 

 attached to the gametophyte, obtaining from it either the whole 

 or a portion of its food. It must, however, be clearly understood 



